A vehicle in new transportation system, having rubber tires which carries a vehicle body and which are adapted to be driven for rotation so as to run the vehicle, is different from a railway vehicle running on rails, and is normally provided with steering guide wheels for steering the rubber tires serving as running wheels along a predetermined track. Accordingly, the guide wheels make contact with a guide rail provided along the track in order to mechanically steer the vehicle.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2003-146204) discloses a bogie for a guide rail vehicle, having guide wheels which are provided to the distal ends of arms projected from a vehicle body and which are mounted on eccentric shafts so as to enable easy adjustment for a degree of projection from the vehicle body in order to steer the vehicle body.
Further, Patent Document 2 (Japanese Patent Laid-Open No. 2003-104198) discloses the configuration that a gap is obtained between a guide wheel which is on the rear side as viewed in the running direction of a vehicle, and a guide surface of a track, and the vehicle can be turned within this gap.
There has been known other Patent Documents, U.S. Pat. No. 6,520,303 (Patent Document 3), U.S. Pat. No. 6,364,215 (Patent Document 4), and WO00/53480(Patent Document 5) which disclose the prior art that a vehicle runs being mechanically steered by such a way that guide wheels make contact with a guide rail which is laid along a track.
However, the above-mentioned mechanical guide mechanisms which are though excellent in safety and reliability, cause the configuration of a bogie of a vehicle, on which wheels and drive mechanism are mounted, to be complicated, and as a result, the mass and the running costs of the vehicle are increased, and further, a guide rail having a strength which is sufficient for supporting the guide wheels, should be laid with a high degree of accuracy over the entire length of a track, resulting in the disadvantages that the construction costs of the track becomes extremely high.
Thus, in order to overcome the above-mentioned disadvantages, there has been proposed a vehicle steering system which does not require, in particular, any guide rail or the like for steering a vehicle (Patent Document 3).
The steering system disclosed In Japanese Patent Laid-Open No. 2002-35144 (Patent Document 6) has several ground elements which store therein data required for driving a vehicle and transmit the same are laid along a track on which the vehicle runs, a control unit mounted on the vehicle consecutively delivers steering instructions on the basis of the data transmitted from the ground elements during running of the vehicle, and accordingly, a steering unit mounted on the vehicle steers the vehicle in response to the steering instructions, thereby it is possible to eliminate the necessity of a guide rail for steering a vehicle so as to be aim at reducing the construction costs and the maintenance costs. Thus, there can be offered the advantage that vibration and noises caused by guide wheels making contact with a guide rail can be reduced.
Explanation will be made of the steering system disclosed in Patent Document 3 with reference to FIGS. 24A, 24B and 25. FIG. 24 is views illustrating the configuration of the steering system, that is, FIG. 24A is a side view and FIG. 24B is a front view, and FIG. 25 is a plan view illustrating a steering unit. Referring to these figures, a vehicle 03 in a new transportation system runs on a track 01. The vehicle 03 is supported by rubber tires 05 carried by bogies 04 which are provided respectively to the front and rear parts of the vehicle 03 through the intermediary of air springs, and runs being driven by rotating motors 06 while the vehicle 03 is steered by an actuator 07.
The steering system comprises ground elements 02, a transmitter 08, a receiver 09, a control unit 010 and a steering unit 020, and turns the rubber tires 05 in order steer the vehicle 03. The ground elements 02 are those which have no electric source, which are laid at predetermined intervals along the overall length of the track 01, and on each of which inherent information is set. Such inherent information includes an identification number of the ground element, position data, track data and control data.
The positional data (on-ground position) relates to the position of a ground element 02, that is, for example, absolute position coordinates or a distance from a reference point. Further, there are set on the ground element 02, as necessary, track data such as a gradient, a curvature, a cant, a turnout portion and the like which exhibit a condition of the track 01 at the point of the ground element 02, as the above-mentioned inherent data.
Such a ground element 02 is electric-powerless, but is adapted to deliver a signal indicating the thus set driving data when an electric power is fed thereto. The ground element 02 is composed of, for example, an electronic circuit including a ROM in which the driving data is stored.
The transmitter 08 is adapted to feed an electric power to the ground element 02 through radio wave propagation, and the receiver 09 receives drive data transmitted from the ground element 02 to which the electric power have been fed. The control unit 010 carries out a predetermined data-processing on the basis of the drive data received by the receiver 09, and delivers a speed instruction and a steering instruction to a drive motor 06 and an actuator 07.
The steering unit 020 which includes the actuator 07 to be operated in response to the steering instruction, is adapted to turn the rubber tires 05, and is composed of an arm 011 pivotally attached at one end to the bogie 04 through the intermediary of a pin the actuator 07 which is attached to the distal end of the arm 011 and which may be electric, hydraulic or pneumatic, a link rod 059, levers 056a, 056b for the left and right rubber tires 05 and a tie rod 057 coupling these levers therebetween.
With the above-mentioned units, when the actuator 07 is operated by the steering instruction from the control unit 010, the arm 011 is rotated around the pin 012 as a center in response to the instruction, and accordingly, the motion of the arm actuates the levers 056a, 056b through the intermediary of the link rod 059 and the tie rod 05 in order to turn the rubber tires 05 leftward or rightward.
This steering system steers the vehicle 03 on the basis of drive data stored in the ground element 02 with no use of any guide rail, and accordingly, it is possible to eliminate the necessity of the guide rail and the like, thereby it is possible to greatly reduce the construction costs of the track 01. Further, since no guide wheels are used, consumables thereof are not required, resulting in reduction of the maintenance costs, and further, since no contact between the guide wheels and the guide rail is caused, there may be offered the advantage that vibration and noise can be reduced.
However, the steering system disclosed in the Patent Document 3 does not use a mechanical steering mechanism including guide wheels and a guide rail, and accordingly, requires safety measures for protection against runaway or come-off of the vehicle from the track in the case of a failure of the steering system or emergency caused by environment disturbance, that is, strong wind, rain, snow or the like. Moreover, since deviation of the running position of the vehicle which runs on the track gradually increases, being caused by a variation in the frictional coefficient of the road surface of the track due to a variation in the environmental disturbance, a number of passengers, abrasion of the tires or the like, it is required to compensate this deviation in order to carry out a safe and high speed operation with a high degree of efficiency.
Thus, it is extremely important to ensure the safety, and to compensate a deviation of a running position, and so forth for the transportation system having a track on which a vehicle runs, being automatically steered along a predetermined running course without using any mechanical steering mechanism including guide wheels and guide rails. The above-mentioned conventional track transportation system has been insufficient for ensuring the safety compensating a deviation of a runninc position with a simple and lightweight configuration, and also capable of diving at a high speed with a high degree of accuracy.    [Patent Document 1] Japanese Patent Laid-Open No. 2003-146204    [Patent Document 2] Japanese Patent Laid-Open No. 2003-104198    [Patent Document 3] U.S. Pat. No. 6,520,303    [Patent Document 4] U.S. Pat. No. 6,364,215    [Patent Document 5] WO00/53480    [Patent Document 6] Japanese Patent Laid-Open No. 2002